The present invention relates to an inspection device for inspecting the electrical characteristics of an IC chip formed on a semiconductor wafer or an electronic component such as an LCD board.
In recent years, with the development of IC manufacturing techniques, the density, integration, and operation speed of semiconductor integrated circuits are increasing. The electrical characteristics of a large number of IC chips formed on a semiconductor wafer are measured before packaging to inspect whether they are normal. To inspect each chip on the semiconductor wafer, for example, a probe device is used. The probe device comprises a POGO pin (name of a contact probe, or a spring contact pin used in trade) ring and a probe card. The POGO pin ring has POGO pins for transmitting, to the probe card, an RF inspection signal sent from a test section for measuring the electrical characteristics of inspection targets. The probe card has probe needles for sending the RF inspection signal sent through the POGO pins to the inspection targets. The tips of the probe needles are brought into contact with the inspection targets, e.g., a plurality of input pads arranged on an IC chip to transmit the RF inspection signal from the test section to the IC chip and to send an RF output signal from an output pad arranged on the IC chip to the test section. The test section measures the electrical characteristics of each IC chip on the basis of the RF output signal.
A conventional probe device will be described in detail below. FIG. 8 is a schematic view showing the arrangement of a general probe device. A semiconductor wafer W as an inspection target is placed on a table 2. The table 2 can be moved in the X, Y, and Z directions by an X-Y-Z stage 4 and is rotatable in the .theta. direction about the Z axis as a central axis. A test head 10 that is a heavy member is attached to freely pivot up and down at a portion above the table 2 through a pair of hinges 8 arranged at the upper portion of a casing 6 of the device main body. The test head 10 is connected to a test portion (not shown) through an electrical connection means 12 which is a bundle of several hundred or thousand wires.
A POGO pin ring 18 which consists of, e.g., glass epoxy-based resin and has a performance board 14 formed of a printed-circuit board, and a large number of POGO pins 16 is arranged at the central portion of the lower surface of the test head 10. An inspection hole is formed at the center of a head plate 20 of the casing 6, and a probe card 24 is attached to the inspection hole. A large number of probe needles 22 are planted in the lower surface of the probe card 24 in correspondence with the layout of the pads of IC chips on the semiconductor wafer. When the test head 10 is pivoted to the main body side, the lower ends of the POGO pins 16 come into contact with pads (not shown) arranged on the upper surface of the probe card 24 and electrically connected with the probe needles 22 to attain electrical conduction between the lower ends of the respective POGO pins 16 and the respective probe needles 22. Since the probe needles 22 of the probe card 24 are so arranged as to contact the respective pads of the IC chips on the semiconductor wafer, an RF inspection signal from the test section is sent to the input pads of the IC chips via the route of the electrical connection means 12, the lower end of each POGO pin 16, and each probe needle 22. RF output signals from the output pads of the IC chips are sent to the test portion through a route reverse to the above route. The test section measures the electrical characteristics of the IC chips on the basis of the RF output signals. The probe needles 22 and the POGO pins 16 are generally arranged in a one-to-one correspondence, and their numbers are the same.
IC chip inspection methods include a characteristic test of executing inspection for all the chips of a semiconductor wafer, and an inspection method of performing inspection using only some pads of one chip, such as a TEG (Test of Element Group) test of inspecting only specific chips, and a burn-in test of checking by applying, e.g., temperature stress whether a potential defect exists.
On the other hand, there are an inspection method of performing inspection upon bringing at once the probe needles into contact with the pads of two or more IC chips on a single semiconductor wafer, and an inspection method of performing inspection upon bringing the probe needles into contact with the pads of all IC chips on a single semiconductor wafer if the inspection must be performed quickly. To perform such inspection, several hundred or thousand POGO pins must be brought into contact with the same number of probe needles at once, and further a large number of signals corresponding to the large number of contacts must be processed. To process such large number of signals, the use of an electrical switching means using a bus buffer and a decoder in the electrical connection path between the POGO pins and the test portion is proposed (Jpn. Pat. Appln. KOKAI Publication No. 6-268035). In this proposed invention, enormous numbers of wire lines and relays are used to process the signals, the test head 10 becomes heavy, and an increase in cost is inevitable.
In addition, arrangement of a mechanical switching means on the wire path between the pads of an inspection target and the test portion is proposed (Jpn. Pat. Appln. KOKOKU Publication No. 7-85196). The mechanical switching means of the proposed invention moves the probe needles, which directly contact the pads of the inspection target. To accurately move the probe needles in contact with the pads of the inspection target, a highly precise structure for attaching the probe needles to the probe card, and a highly precise control mechanism for moving the probe needles are required because the areas of the pads of the inspection target and the interval between the pads are very small.
Recently, the number of IC chips of a single semiconductor wafer is increasing due to an increase in semiconductor wafer size. To cope with this trend, a larger number of probe needles must be brought into contact with a larger number of pads of the inspection target in inspection. Therefore, the necessity for solving the above problems is increasing.
The present invention has been made to effectively solve the above problems.
It is an object of the present invention to provide a simple, light-weight inspection device using no test head which is a heavy member and is necessary for the conventional device.
It is another object of the present invention to simplify the structure of the inspection device by simplifying and facilitating the design and manufacture of a structure for attaching probe needles to a probe card and a control mechanism for moving the probe needles with the use of a combination of the probe card used in the conventional device and a mechanical path switching means.
It is still another object of the present invention to avoid degradations in resistance and impedance on a signal path by shortening the signal path, and perform highly precise measurement.
It is still another object of the present invention to perform an efficient inspection by arranging a plurality of mechanical path switching means and circumferentially moving them.